The Environmental Protection Agency (EPA) is approving Maryland's regional haze progress report, submitted on August 9, 2017, as a revision to its State Implementation Plan (SIP). Maryland's SIP revision addresses Clean Air Act (CAA) provisions and EPA regulations that require each state to submit periodic reports describing the State's progress towards reasonable progress goals (RPGs) established for regional haze and to make a determination of the adequacy of the State's existing regional haze SIP. The EPA is approving Maryland's determination that the State's regional haze SIP is adequate to meet the RPGs for the first implementation period.